Method for washing adsorbents



Nov. 20, 1956 J. E. PENICK 2,7

METHOD FOR WASHING ADSORBENTS Filed Nov. 19, 1952 3 Sheets-Sheet 1 19 21INVEN TOR.

Jae E Pen ic/fl Nov. 20, 1956 J. E. PENICK METHOD FOR WASHING ADSORBENTSFiled Nov. 19. 1952 3 Sheets-Sheet 2 WASHER Emil Nov. 20, 1956 J. E.PENICK METHOD FOR WASHING ADSORBENTS Filed Nov. 19; 1952 3 Sheets-Sheet3 INVENTOR .LT Penicfif iGf/VT United States Patent METHOD FOR WASHINGADSORBENTS Joe E. Penick, Augusta, Kans., nssignor to Socony Mobil OilCompany, Inc., a corporation of New York Application November 19, E52,Serial No. 321,371

7 Claims. (Cl. 196147) This invention is concerned with a method fortreating liquid hydrocarbons and mineral oils, particularly lubricatingoils, and lower boiling petroleum fractions with solid adsorbents forthe purpose of removing small amounts of impurities. It is especiallyconcerned with the washing of spent adsorbents which exist at atemperature above the boiling point of the wash solvent after use insuch processes.

Typical of the processes to which this invention applies is thecontinuous percolation of liquid hydrocarbon oils of low asphalt contentupwardly through a downwardly gravitating columnar mass of adsorbent toeffect removal of small amounts of impurities and color bodies from theoil.

The adsorbent used in this invention should be made up of palpableparticles of size within the range about 4-l()0 mesh and preferably 1060mesh and still more preferably l530 mesh by Tyler Standard ScreenAnalysis. The particles may take the form of pellets, capsules, pills,spheres, or the like, or granules of irregular shape such as areobtained from grinding and screening. The terms adsorbent in palpableparticulate form and palpable particle form adsorbent as employed hereinin describing and claiming this invention are intended to genericallycover particles of any or all of these shapes having substantial size asdistinguished from finely divided particles.

In processes of the aforementioned type, the used adsorbent, afterremoval from the treating zone, will have tarry or coke-likecarbonaceous contaminants and color bodies deposited thereon. This usedadsorbent will also carry with it from the treating zone a substantialamount of cycle oil. The term cycle oil is used herein in describing andclaiming this invention broadly to refer to the sum total of the oildischarged from the treater in the adsorbent pores, in the voids betweenthe granules in the discharge stream and the supernatant oil or any oneor more of them. It is necessary that all of these materials be removedso that the adsorbent may here-used in treating further oil. This isnormally most easily accomplished by burning the objectionablecomponents off the adsorbent with an oxygen-containing gas. However, itis not desirable to burn the cycle oil in this manner since this wouldresult in increased operating costs for the process and, obviously,lower yields of purified products. For these reasons it is usuallynecessary to wash the cycle oil from the adsorbent with a suitable washsolvent before burning and then separate solvent and oil and return theoil to the treating zone. This is generally accomplished by passing asuitable wash solvent, such as naphtha, upwardly through a columnar massof the adsorbent to dissolve the cycle oil from the adsorbent. A columnor body of liquid wash solvent is normally provided above the columnarmass of adsorbent to provide for the disengaging of adsorbent fromsolvent, so that there will not be excessive carry-over of adsorbentwith outgoing solvent. A difiiculty occurs here where, as is frequentlythe case, the operating temperature of the treating zone is abovePatented Nov. 26, 1-956 2 the boiling point of the solvent being used inthe washing zone. If the hot adsorbent from the treating zone is merelydischarged into the top of the washing zone it will first drop on theupper surface of the column of solvent therein. The solvent willimmediately begin to boil near the upper surface of the column and thisboiling will cause excessive entrainment of the adsorbent so charged,in-the used solvent stream withdrawn from the column. Afurtherdifliculty occurs Where there is a high temperature in the Washing Zone.When the temperature in the washing zone is too high, for example, atemperature near the treating temperature, substantial amounts of colorbodies are removed from the adsorbent by the Washing solvent. When thesolvent is later separated from the oil recovered from the adsorbent,these color bodies remain with the recovered cycle oil and render itsubstantially darker than the oil feed to the treater, whereas withoutremoval of the color bodies from the adsorbent, recovered oil in theprocess would have a color not substantially darker and usually somewhatlighter than the fresh feed to the treater. This contamination of therecovered oil is undesirable even where the recovered oil is passed tostorage rather than recycled. Since, in the usual case, the amount ofoil recovered in the washer is an appreciable fraction of the total feedto the treater, the treating capacity is greatly reduced by excessiveamounts of color bodies in the cycle oil. In some cases the recoveredoil may be so dark as to render its recycling to the treater entirelyunfeasible.

A major object of this invention is to provide animproved continuouscyclic percolation process for treatment of hydrocarbons at elevatedtemperatures which overcomes the above-described difficulties.

Another object of this invention is to provide a method for washing aspent adsorbent of palpable particulate ice ' form used for the removalof impurities from liquid oils at high temperatures and bearingcarbonaceous contaminants, color bodies and cycle oil, which avoidsexcessive entrainment of the adsorbent in the wash solvent.

Another object of this invention is to provide, in a mineral oildecolorizing process, a method for washing spent palpable particle formadsorbents bearing carbonaceous contaminants, color bodies and cycleoil, which provides for dissolving the cycle oil in a wash solventwithout dissolving amounts of color bodies therein suificient to causeexcessive loss in capacity in the oil decolorizing step.

These and other objects of the invention will be apparent from thefollowing discussion of the invention.

In one aspect of this invention, a downwardly gravi tating columnar massof adsorbent of palpable particulate form is maintained within the lowersection of a confined washing zone. A suitable wash solvent, such asnaphtha, is passed upwardly through this columnar mas to dissolve anycycle oil from the adsorbent in the wash solvent. Wash solvent isdischarged from the upper end of the columnar mass and passes upwardlythrough the upper section of the washing zone or a disengaging zone as acolumn of liquid above the columnar mass of adsorbent. Spent adsorbent,bearing carbonaceous contaminants, color bodies and cycle oil, andexisting at a temperature above the boiling point of the. solvent, ischarged as a plurality of streams to the upper section of the washingzone and passed into heat exchange relationship with the liquid columntherein whereby the adsorbout is cooled to a temperature substantiallybelow that at which it entered the washing zone and a portion of thesolvent in the liquid column vaporizes. This cooled adsorbent is thenpassed to the columnar mass of adsorbent and liquid and vaporizedsolvent are removed as separate streams from the upper section of thewashing zone. The heat exchange relationship between the incomingadsorbent and the outgoing liquid column of solvent may be either director indirect and in either case the cooling is accomplished by the latentheat capacity of the solvent plus its sensible heat capacity. In everycase a sufiicient percent of the solvent is vaporized to do the requiredamount of cooling. In some cases all of the cooling required to reducethe temperature of the adsorbent to a level below that at whichprohibitive amounts of color bodies or other undesired componentsdissolve in the wash solvent may be accomplished by this vaporizationand heat exchange with the liquid column. In others a part of thecooling may be done by outside cooling applied to the upper section ofthe columnar mass or by outside cooling applied to the liquid column. Instill other cases a part of the required cooling may be done within thecolumnar mass by control of the inlet temperature and rate of washsolvent supply to the lower section of the columnar mass.

This invention will be best understood by referring to the attacheddrawings, of which Figure l is an elevational view showing theapplication of this invention to a continuous percolation process forthe treatment of liquid hydrocarbon oils with solid adsorbents,

Figure 2 is an elevational view, partially in section, showing theinternals of a typical washing vessel adapted to be used in thisinvention,

Figure 3 is an elevational view, partially in section, showing the uppersection of a washer employing a modified form of this invention,

Figure 4 is an elevational view, partially in section, illustrating asecond modification of this invention, and

Figure 5 is an elevational view, partially in section, illustrating athird modification of this invention.

All of these drawings are diagrammatic in form and like parts in allbear like numerals.

Turning to Figure 1, there is shown therein a portion f a continuouspercolation system similar to that described in U. S. patentapplication, Serial Number 177,408, filed August 3, 1950, now Patent No.2,701,786. Adsorbent of palpable particulate form gravitates from asupply hopper 10 into the upper section of a confined treating zone 11through a conduit 12. Typical adsorbents which may be employed are-fullers earth, bauxite, bentonite and bone char, charcoal, magnesiumsilicate, heat and acid activated kaolin, activated carbon and syntheticsilica or alumina or silica-alumina gel adsorbents. Adsorbent passesdownwardly through the treater as a columnar mass. Liquid hydrocarboncharge oil, which may consist of a lubricating oil or fuel oil of lowasphalt content, is heated in heater 13 and passes into the lowersection of treater 11 through conduit '14. Charge oil passes upwardlythrough the olumnar mass of adsorbent in the treating zone to effect theremoval of small amounts of undesirable impurities from the oil. Typicalof the purposes for which the oil may be treated are decolorization,neutralization, removal of suspended, colloidal or dissolved impuritiessuch as carbon or coke or oxygen and nitrogen containing impurities andother gum form ing compounds, and improvement of the demulsibilityproperties of the oil. This invention will be described in connectionwith a mineral oil decolorization process for purposes of clarity. Thepurified oil is removed through conduit 33. The temperature in thetreating zone may fall within the range of atmospheric temperature to700 F. but should generally be maintained below the flash point of theoil as measured by the A. S. T. M. Cleveland open cup method. It ifrequently desirable to maintain the treating temperature at an elevatedlevel substantially above atmospheric temperature and often at a levelabove the boiling point of the wash solvent used in the washing stepdescribed hereinbelow. This invention is particularly applicable to thelatter case and is concerned only with cases where the treating is atelevated temperatures. The adsorbent, after use in the treating zone,will have deposited thereon a coky or tarry carto treater l1.

bonaceous contaminant, at least a part of which consists of theundesirable components, such as color bodies, desired to be removed fromthe hydrocarbon oil. This adsorbent is removed from the treating zone 11through conduit 15 and carries with it adhering liquid oil which it isdesirable to recover and return to the treating zone. The spentadsorbent passes to a flow dividing box 16 wherein stream 15 is splitinto a plurality of maller streams 17 which pass into the upper sectionof washing zone 18. A downwardly gravitating columnar mass of adsorbentis maintained within the lower section of zone 18. Washing solvent issupplied to the lower section of this columnar mass from an accumulationthereof within a tank 19 by means of conduit 20 and pump 21. Suitablewash solvents include petroleum naphtha boiling within the range 100-400F., carbon tetrachloride, normal heptane, normal octane, and carbondisulfide. A paraffinic naphthat boiling within the range about ZOO-300F. is generally perferable. The solvent passes upwardly through thecolumnar mass of adsorbent and dissolves cycle oil from the adsorbent.Wash solvent with dissolved cycle oil passes through the upper sectionof zone 18 as a column of liquid above the columnar mass of adsorbent.Spent adsorbent in streams 17, bearing carbonaceous contaminants, colorbodies and cycle oil, passes into heat exchange relationship with theliquid column in the upper section of the washer whereby the adsorbentis cooled and a portion of the solvent in the liquid column isvaporized. The cooling of the adsorbent within the washing zone must besuch that the temperature of the adsorbent is sufiiciently low toprevent removal of excessive amounts of the color bodies from theadsorbent during the washing step. By excessive amounts of color bodiesis meant such amounts as would so contaminate the cycle oil that theproduct yields from the treater per unit weight of adsorbent throughputwould fall to an impractically low level, for example, less than aboutseventy percent of that obtainable on the basis of one hundred percentfresh oil charge to the treater. In general, the amount of color bodiesremoved from the spent adsorbent should not exceed about fifty percent,and should preferably be below about twenty-five percent by weight ofthe total color bodies on the spent adsorbent leaving the treater (i.e., above those which would give a cycle oil of ame color as the freshfeed). In many operations it is preferred to exclude resolution of anysubstantial amount of color bodies in the washing step, i. e., an amountof color bodies 'which renders the recovered cycle oil substantiallydarker than the fresh oil supplied to the treater. Inert gas is admittedto dividing box 16 by conduit 22 and passes downwardly through conduits17 at a pressure suflicient to prevent solvent from entering the lowerends of passages 17. Vaporized solvent is Withdrawn from the uppersection of the washer through passage 23 and condensed by condenser 24and then supplied to accumulator 19. Liquid solvent passes from theupper section of the washer 18 into a fractionating zone 25 by means ofpassage 26. In the fractionator 25 solvent is taken as an overhead vaporstream which passes outwardly through passage 27 and is condensed bycooler 28 and then passed to the accumulation in tank 19. Liquid cycleoil, freed of solvent, is Withdrawn from the bottom of 25 by pipe 29,heated by heater 30 and returned with the liquid charge Washed adsorbentis removed from the lower section of the washing zone by conduit 31. Theadsorbent from 31 may then be passed to a suitable regeneration meanswherein the carbonaceous contaminants and color bodies are removed. Onemethod of regeneration is by controlled burning of the contaminants andcolor bodies with an oxygen-containing gas. Regenerated adsorbent maythen be returned to hopper 10 through conduit 32.

Figure 2 illustrates the internals of the washer 18. Extending acrossthe upper section of the washing zone 18 is an open topped trough orchannel 34 for liquid withdrawal. The channel 34 has a plurality ofhorizontally spaced-apart orifices 35 lying on substantially the samehorizontal line therethrough at a level intermediate the top and bottomof 34. One end of trough 34 connects into receptacle 36 and liquidwithdrawal conduit 26 extends from 36 at a level below the bottom of 34.This system of liquid withdrawal is described and claimed in U. S.patent application, Serial Number 265,832, filed January 10, 1952.Across the lower section of vessel 18 is a solvent plenum chamber 37defined by vertically spaced-apart transverse partitions 38 and 39extending across vessel 18. Conduits 40 extend through the plenumchamber. A plurality of uniformly spaced-apart liquid nozzles 41 extendthrough partition 38 into the lower section of the columnar mass ofadsorbent 42 within the lower section of'vessel 18. Suitable nozzles aredescribed and claimed in U. S. patent application, Serial Number237,265, filed July 17, 195 1. A plurality of uniformly spaced apartadsorbent charge conduits 17 extend into vessel 18 to a levelsubstantially below the horizontal row of orifices 35 in channel 34.Passages 17 have fins 43 on their outer peripheries as an aid to heattransfer. The upper section of vessel 18 is of greater lateraldimensions than the lower section and contains a column of liquidsolvent 44 above columnar mass 42. Extending across vessel 18 at thebottom of the larger upper section of the vessel is a perforated pipe'45 with -a screen 46 thereon. A conduit 47 extends into liquid column44 at a level above pipe 45. Pipes 45 and 47 are joined together outsideof vessel 18 and connect to pipe 48 which in turn connects into conduit20. A level control device is provided to control the surface level ofcolumnar mass 42 between the levels of pipes 45 and 47. Pressure taps 49and 50 pass through the wall of vessel 18 at vertically spaced-apartpoints shortly above and shortly below the desired surface level of 42.These taps connect to a manometer 51 which measures the pressure dropdue to oil flow through the section of vessel 18 between taps 49 and 50.Thus, if the surface level of 42 rises, the pressure drop will increase,if the level drops it will decrease. Controller 52 is adapted to adjustthe position of valve 53 in adsorbent withdrawal line 15 in conformitywiththe pressure drop shownby manometer 51. Thus, the greater thepressure drop the further controller 52 will open valve 53. The surfacelevel of 42 will, therefore, be maintained constant within a narrowrange of levels. This method of control is described and claimed in U.S. patent application, Serial Number 237,190, filed July 17, l951, nowabandoned.

In one operation of the apparatus of Figure 2, valves 54 and 55 in pipes45 and 47 are kept closed. Wash solvent is pumped from accumulator 19through, passage 20 into plenum chamber 37. Solvent passes from theplenum chamber by means of nozzles 41 into the lower section ofdownwardly gravitating columnar mass of adsorbent 42 maintained withinwashing zone 18. Solvent passes upwardly throughv mass 42 and washescycle oil from the adsorbent therein. Solvent with dissolved cycle oilis discharged from the upper surface of columnar mass 42 and passesthrough the upper section of zone 18 as a column of liquid 44 abovecolumnar mass 42.- Liquid is withdrawn from 44 through orifices 35 intrough 34, so that the upper surface of column 44 is maintained at alevel below the top of zone 18 and a gas space 56 is defined abovecolumn 44. Spent adsorbent of palpable particulate form, at an elevatedtemperature above the boiling point of the Wash solvent and bearingcarbonaceous contaminants, color bodies and liquid cycle oil is passedinto the upper section of zone 18 as a plurality of streams throughpassages 17. Passages 17 terminate at a level above the upper surface ofcolumnar mass 42 and substantially below the upper surface of liquidcolumn 44. Indirect heat exchange takes place between the adsorbentstreams in passages 17 and the upper section of liquid column 44 throughthe walls of passages 17. As a result of this heat exchange, the adsorbent is cooled to a temperature at least below the boiling point ofthe solvent and preferably below the temperature at which substantialamounts of color bodies will be removed by the washing solvent. Due tothis cooling a portion of the solvent in the liquid column vaporizes andpasses into gas space 56. Cooled adsorbent drops from the lower ends ofpassages 17 onto the surface of columnar mass 42. It will be noted thatthis method avoids the entrainment of adsorbent in the liquid flowinginto trough 3-4, since all the boiling of solvent and resultantdisruption of the liquid column 44 occurs above the lower ends of 17Where there is no or very little adsorbent in the liquid-column. Liquidsolvent with dissolved oil is withdrawn from the upper section of column44 through orifices 35 into trough 34, from which it passes intoreceptacle 36 and then through conduit 26 to fractionator 25 aspreviously described. Vaporized solvent passes from gas space 56 abovecolumn 44 by means of conduit 23 and passes to tank 319 aftercondensation by condenser 24. Washed adsorbent passes through conduits40 to the lower end of vessel 18 and is removed from the vessel byconduit 15 so as to promote downward movement of the adsorbent throughcolumnar mass 42.

An alternative method of operation of the apparatus of Figure 2 is toopen valve 54 while leaving valve 55 closed so as to charge solvent tothe upper section of columnar mass 42 through pipe 45. This provides foran additional quantity of cool solvent in the upper section of thewashing zone 18 and therefore assists in the cooling of the streams inpassages 17. The same effect may be obtained by opening valve 55 whilevalve 54 is left closed. Additional cool solvent is then provided at alevel above the upper surface of columnar mass 42. Also, part of stream26 can be cooled and recycled to either 45 or 47 to aid in controllingtemperature of column 44. Both of these latter systems are especiallydesirable where it is found that excessive amounts of color bodiesdissolve in the wash solvent used at the temperature at which theadsorbent exits from the passages 17 when additional cooling of thesolvent is not used. Normally, however, the indirect cooling throughpassages 17 cools the adsorbent to a temperature substantially below theboiling point. Only the solvent near the surface of column 44 will be atthe boiling point, the solvent near the bed surface being at a suitablewashing temperature at which substantial amounts of color bodies do notdissolve. This will be attained in many operations without addition ofextra cool solvent through either 46 or 47. These latter streams areonly necessary where the indirect cooling through passages 17 and thecooling accomplished as the adsorbent falls through the portion ofliquid column 44 below passages 17 to columnar mass 44, is insufficientto cool the adsorbent to a suitable washing temperature at whichexcessive amounts of color bodies do not dissolve in the solvent.

Also, in a modified form of this invention, the hot adsorbent from thetreater may be substantially cooled by vaporization of a part of thesolvent and by heat ex change with the liquid body above the solvent,for example, from a treating temperature of 350 F to 200 F., while theaverage washing temperature is maintained at a still lower temperature,for example, about F., at which excessive amounts of color bodies arenot removed from the adsorbent. This is accomplished by control of therate and temperature of the Washing solvent supply to the lower sectionof the columnar mass. In this operation sufiicient heat is removed fromthe adsorbent before it is discharged into the body of liquid above thecolumnar mass by vaporization of solvent to at least prevent boiling ofthe solvent when the adsorbent is so discharged. In this form of theinvention it is important that the heat capacity of the solvent suppliedto the washing zone between its inlet temperature and the temperature ofthe partially cooled adsorbent falling onto the columnar mass be atleast equal to the heat capacity of the adsorbent over the sametemperature range, and preferably the heat capacity of the solventshould be ten per cent in excess of the amount above indicated. Heatcapacity is here used to indicate the product of the specific heat ofthe particular material, the weight charged to the washer per unit timeof the particular material and the specified temperature range all inconsistent units. Under the conditions specified, the adsorbent iswithdrawn from the washing zone at substantially the solvent inlettemperature and the solvent leaves the top of the columnar mass at orsomewhat below the temperature of the partially cooled adsorbent fallingfrom the liquid body onto the columnar mass. The advantages of this lastmentioned method lies in the ability thereby to conduct the washingoperation at suitably low washing temperatures, while the liquid body ismaintained at a somewhat higher temperature where the viscosity of theoil-containing solvent than it would be if the liquid body were cooledall the way to the desired washing temperature. As a result, the fluidviscosity in the zone where the liquid is disengaged from the spentadsorbent feed is maintained at a level better suited for effecting thedisengagement without adsorbent entrainment in the effluent liquid.

The upper section of washing zone 18 is of greater lateral dimensionsthan the lower section. This is to provide for the additional volumeadded to the washing solvent by dissolving the cycle oil from theadsorbent and for the higher viscosity of the solvent-oil mixture. Byexpanding the upper section in this manner, the superficial velocity ofthe liquid in the washing zone 13 is maintained at a level below thatwhich would disrupt columnar mass 42 or carry over adsorbent into trough34 even though the total liquid volume increases through the washingzone and the viscosity increases. While it is preferable, it is notnecessary to this invention that the upper section of vessel 18 beexpanded in this manner. The expansion, of course, becomes moredesirable when solvent is added through pipes 45 and 47. Inert gas, suchas flue gas, may be passed through pipes 17 with the adsorbent at apressure suflicient to keep any liquid from liquid column 44 fromentering the lower ends of pipes 17 and vaporizing therein. In a lesspreferred form of the invention, pipes 17 may be shortened so that theyextend only a short distance below the surface of column 44. Then mostof the heat exchange between adsorbent and solvent will be direct ratherthan indirect. There may be boiling near the surface of the bed withthis system, however, which may lead to entrainment of the adsorbent inthe effiuent solvent as previously stated. A superior method ofaccomplishing this invention by direct heat exchange is shown in Figureand described herein'oelow.

Figure 3 illustrates an alternative method of this invention which isespecially adapted to control the temperature of the columnar mass ofadsorbent 42 below the temperature at which substantial amounts of colorbodies dissolve in the solvent from the adsorbent. The washer 13 isdivided into three separate superimposed sections or zones, 21 lowerwashing zone 57, a cooling zone 58 thereabove of lateral dimensiongreater than zone 57, and a disengaging zone 55 above the cooling zoneand of greater lateral dimensions than the cooling zone. Columnar massof adsorbent 42 extends throughout washing zone 57 and cooling zone 58while liquid column of solvent 44 is maintained within disengaging zone59 with gas space 56 thereabove. Liquid solvent passes upwardly throughcolumnar mass 42 to dissolve the cycle oil from the adsorbent therein.Solvent with dissolved cycle oil passes from the upper end of columnarmass 42 and cooling zone 58 into disengaging zone 59 and then throughzone 59 as a liquid column or body 44 from which entrained adsorbentsettles. Adsorbent is supplied to the washer in the same manner as inFigure 2, entering through a plurality of confined passages 17 andcooled by indirect heat exchange with liquid column 44 to a temperatureat least below the boiling range of the solvent, as a result of which aportion of the solvent in 44 is vaporized. Vaporized solvent iswithdrawn through conduit 23 and liquid solvent through conduit 26. Theadsorbent dropping onto the upper surface of columnar mass 42 frompassages 17 may still be at a temperature above the temperature at whichexcessive amounts of color bodies will dissolve in the solvent. For thisreason solvent is withdrawn from the upper section of cooling zone 58 ata level adjacent the upper surface of columnar mass 42 through conduit60. The solvent so withdrawn is cooled by cooler 61 and then injectedinto an intermediate level in the columnar mass 42 at the lower end ofcooling zone 58 by means of perforated pipe 62. The rate of solventcirculation through 60 and 62 and the temperature of the intermediatecooling by cooler 61 should be controlled so that the upper section ofcolumnar mass 42 is reduced below the temperature at which there isexcessive dissolving of color bodies in the solvent, and preferablybelow the temperature at which substantial amounts of color bodiesdissolve in the solvent.

Figure 4 illustrates an apparatus which accomplishes the method ofFigure 3 in a slightly different manner. Rather than cooling the uppersection of columnar mass 42 by direct heat exchange with cooled solvent,the method of Figure 4 accomplishes this cooling by indirect heatexchange with a suitable cooling fluid, such as cold water, circulatedthrough cooling coils 63.

Figure 5 illustrates a process of this invention wherein the cooling ofthe incoming adsorbent to the washer is accomplished by direct heatexchange rather than indirect heat exchange with the liquid solventcolumn as described previously. Adsorbent charge conduits 17 enter theupper section of the washer and terminate at uniformly spaced-apartpoints on a common level above the upper surface of liquid column 44.Tubes 64 of greater lateral dimensions than'conduits 17 and open on topand bottom are attached to the lower ends of conduits 17 and extend froma level above the upper surface of liquid column 44 to a level asubstantial distance below the surface of 44. Since tubes 64 are open ontop and at the bottom, solvent will seek its own level therein. The'hot, spent adsorbent is discharged from conduits 17 into the solventwithin tubes 64 where cooling of the adsorbent takes place by directheat exchange with the solvent, as a result of which a portion of thesolvent is vaporized. If any boiling of the solvent occurs within tubes64, it will not result in entrainment of the adsorbent in the effluentsolvent, since tubes 64 shield the boiling solvent from the liquidsolvent draw-off through orifices 35. The remainder of the operation ofthe process of Figure 5 is similar to that of Figure 2. The variousmodifications of the process described in connection with Figure 2 areequally applicable in the process of Figure 5. Additional cooling may besupplied by cooling a portion of the solvent-oil mixture or by suitablycontrolling the solvent feed rate to perform a portion of the cooling inthe columnar mass.

The various parts of apparatuses capable of conducting the method ofthis invention may, of course, take other forms than those shown anddescribed hereinabove. The upper section of the washing vessel need notbe of greater lateral dimensions than the lower but the entire washingvessel may have the same lateral dimensions. The expanded upper sectionis preferable, however, since it minimizes the possibility of adsorbententrainment by reducing the velocity of the solvent before it iswithdrawn. The expanded section is especially desirable where liquidsare added to the upper section of the washer, as in Figure 2 when valve54 is open. The fins 43 in conduits 17 are not necessary but aredesirable to increase the rate of heat transfer from the adsorbenttherein. Where large amounts of cycle oil are removed from the treatingzone with the adsorbent, it may be desirable to drain the ad- 9 sorbentin a suitable drainer, such as a continuous moving screen before passingit to the washer and thereby decrease the load on the washer.

Where the indirect heat exchange method of cooling the adsorbent isused, the distance which conduits 17 extend below the surface of liquidcolumn 44 will depend mainly on the temperature of the incomingadsorbent, the overall heat transfer coeificient, and the properties ofthe solvent. Generally, the pipes 17 should extend a distance within therange about two to six feet below the surface of liquid column 44. Whenthe direct heat exchange method of Figure is used, the distance of tubes64 below the surface of column 44 will depend on the temperature of theincoming adsorbent and the specific heat and heat of vaporization of thesolvent. Generally, tubes 64 should extend a distance within the rangeabout one foot to four feet below the surface of column 44. The factthat a method is characterized as being an indirect heat exchange methoddoes not indicate that some direct heat exchange does not occur; itmerely means that the major portion of the heat exchange is indirect.Conversely, when the method is characterized as direct heat exchange itdoes not negative indirect exchange.

When the indirect heat exchange method for cooling the incomingadsorbent is used, it may be desirable to pass inert gas in with theadsorbent as previously described. When such inert gas is employed, thepressure thereof should be maintained sufficient to prevent liquidsolvent from entering the lower ends of the adsorbent charge conduitslike 17. In many applications this inert gas may not be needed,particularly where the rate of adsorbent flow to the pipes 17 iscontrolled so that the adsorbent falls freely through pipes 17.

Where color bodies constitute one of the impurities re moved from thehydrocarbon feed in the treating zone, the temperature of the adsorbentcolumn should be maintained preferably below the temperature at whichthe color bodies are removed from the adsorbent in substantial amount,i. e., an amount suificient to render the color of the recovered cycleoil substantially darker than that of the fresh oil feed to the treater.Substantially darker cycle oil than the fresh feed, when recycled, willresult in decreased yields of oil product of specified color per unit ofadsorbent throughput. It has been found feasible in many operations toaccept a product yield down to seventy per cent of that obtainable onone hundred per cent fresh oil feed and to tolerate a cycle oil ofdarker color than the fresh feed. In no case, however, should thetemperature in the washing column be perrnitted to rise to a level atwhich excessive amounts of color bodies would be removed from theadsorbent, i. e., amounts sufiicient to result in unfcasibly low productyield from the treater. in general, the amount of color bodies removedby the solvent in the washing operation shouldbe maintained below fiftyper centby weight of the color bodies on the adsorbent. The temperatureat which substantial or excessive color bodies will be dissolved can bedetermined by routine tests for any given system. As an example in thecase of a 30- to 60' mesh granular fullers earth adsorbent which hasbecome partially spent in decolorizing a bright stock oil from anoriginal color of 180 Lovibond to a finished color of 90 Lovibond, thecycle oil amounted to about 0.12 part per part of oil product and toabout 1.8 parts by weight per part of adsorbent. Using'a paraflinicnaphtha wash solvent boiling in the range about 210330 F., suflicientcolor bodies were removed from the adsorbent to render the cycle oilcolor substantially darker than that of the original oil feed to thetreater at Washing zone temperatures above 200 F.

The volumetric ratio of solvent to adsorbentcharged to thecolumnar massin the washer may vary within the range about 0.25 to 3.0, andpreferably 0.4 to 1.5. The length of the columnar mass in the washershould, be about 5 to 20 feet, while the length of the liquid body abovethe columnar mass should be about 1 to 6 feet in height.

As an example of the method of this invention, itsuse in washing -28 to60 mesh adsorbent fullers earth in, a continuous mineral oil percolationprocess will be discussed. The method of operation was that described inconnection with Figure 2 withvalves 54 and 55 closed. Adsorbent wascharged at a temperature of about 360 F. through passages which extendeda distance of three feet below the surface of liquid column 44. Theadsorbent contained about 1.2 volumes of adhering liquid oil per volumeof adsorbent. Adsorbeut was charged at a rate of one cubic foot per hourand solvent at a rate of 0.4 cubic foot per hour. The solvent used waspetroleum naphtha boiling within the range about 2l0300 F. The adsorbentwas cooled to a temperature of about 215 F. on discharge from pipes 17and the columnar mass of adsorbent was maintained at a temperature ofabout F.

This invention should be understood to cover all changes andmodifications of the examples of the inventionherein chosen for purposesof disclosure which do not constitute departures from the spiritand'scope of the invention.

I claim:

l. A continuous process for washing hot, spent adsorbent of palpableparticulate form, having been used for purifying liquid hydrocarbon oilsand bearing carbonaceous contaminants, color bodies and cycle oil, whichcomprises: maintaining a downwardly gravitating columnar mass ofadsorbent within the lower section of a confined washing zone,maintaining a column of liquid solvent of sufiicient height to disengageadsorbent from the liquid solvent above said columnar mass within theupper section of the washing zone, passing cool washing solvent upwardlythrough said columnar mass to re move cycle oil from the adsorbenttherein, passing washing solvent after passage through the columnar massupwardly through said liquid column, introducing additional cool washingsolvent at an intermediate level in said liquid column, passing aplurality of streams of hot, spent adsorbent downwardly through theliquid column and in heat exchange relationship therewith to effectcooling of'the adsorbent and vaporize a portion of the solvent,discharging said streams of adsorbent onto the upper surface of saidcolumnar mass, removing liquid solvent from the upper section of saidcolumn, maintaining the adsorbent streams out of lateral communicationwith that portion of the liquid solvent column from which liquid solventis removed during that portion of the heat exchange wherein solvent isvaporized, removing vaporized solvent from the upper section of saidzone at a level above the upper surface of said column, and removingwashed adsorbent from the lower section of said columnar mass.

2. A continuous process for the removal of cycle oil from spentadsorbent of palpable particulate form bearing carbonaceous contaminantsand color bodies by washing with a washing solvent, which comprises:maintaining a columnar mass of spent adsorbent within the lower sectionof a confined washing zone, passing a liquid washing solvent upwardlythrough said columnar mass to dissolve the cycle oil on the adsorbenttherein, discharging the solvent containing dissolved oil from the upperend of the columnar mass and passing said solvent through the uppersectionof the washing zone as a liquid column, passing a plurality ofstreams of spent adsorbent existing at a temperature above the boilingpoint of the solvent through a plurality of confined passagesterminating at a common level substantially below the upper surface ofsaid liquid column but above the upper surface.

of said columnar mass whereby said plurality of streams will be cooledby indirect heat exchange'with said liquid column and a portion of thesolvent in said column will be vaporized, said passages being of suchlength that said vaporization is substantially completed beforeadsorbent is discharged therefrom, passing an inert gas through saidpassages with the adsorbent at a pressure suflicient to prevent anyliquid from said column entering the lower ends of said passages,passing adsorbent from the lower ends of said passages onto the uppersurface of said columnar mass, removing liquid solvent with dissolvedoil from the upper section of the liquid column, removing vaporizedsolvent from the upper section of said washing zone at a level above theupper surface of the liquid column and removing washed adsorbent fromthe lower section of said columnar mass.

3. A continuous process for the removal of cycle oil from a spentadsorbent of palpable particulate form, having carbonaceous contaminantsand color bodies deposited thereon and existing at an elevatedtemperature, by means of a wash solvent, which comprises: maintaining adownwardly gravitating columnar mass of spent adsorbent within the lowersection of a confined washing zone, passing washing solvent from aconfined accumulation thereof exterior to the washing zone into thelower section of the columnar mass, passing the washing solvent upwardlythrough the columnar mass to dissolve the cycle oil from the adsorbenttherein in the washing solvent, discharging washing solvent withdissolved oil from the upper surface of the columnar mass and passingthe washing solvent upwardly through the upper section of the washingzone as a liquid column above the columnar mass of adsorbent, passing aplurality of streams of spent adsorbent with cycle oil at a temperatureabove the boiling point of the solvent and above the temperature atwhich excessive amounts of color bodies dissolve in the solvent intosaid washing zone through a plurality of uniformly spaced-apart confinedpassages terminating at a common level above the upper surface of saidcolumnar mass of adsorbent but substantially below the upper surface ofthe liquid column so that the spent adsorbent is cooled by indirect heatexchange with the liquid column to a temperature below the temperatureat which more than about fifty percent by weight of the color bodies onthe adsorbent are redissolved by the solvent and a portion of thesolvent in the liquid column is vaporized, accomplishing all of saidadsorbent cooling which results in vaporization of solvent prior todischarge of the adsorbent from said passages, discharging the spentadsorbent from said passages onto the upper surface of said columnarmass of adsorbent, withdrawing liquid solvent with dissolved oil fromthe upper section of said liquid column, passing the solvent sowithdrawn to a fractionating zone and separating the solvent from theoil in the fractionating zone by vaporizing the solvent, removing liquidoil from the lower section of the fractionating zone, removing vaporizedsolvent from the upper section of the fractionating zone and condensingthe solvent, passing the condensed solvent to said confined accumulationof solvent, removing vaporized solvent from the upper section of saidwashing zone at a level above the upper surface of the liquid column,condensing the vaporized solvent from the washing zone and passing thecondensed solvent to said confined accumulation thereof and removingwashed adsorbent from the lower section of said columnar mass.

4. A continuous process for removing hydrocarbon cycle oil, by means ofa wash solvent, from a spent adsorbent of palpable particulate formbearing carbonaceous contaminants and color bodies as well as cycle oilexisting at a temperature above the boiling point of the wash solventand above the temperature at which excessive amounts of color bodiesdissolve in the wash solvent from the adsorbent, which comprises:maintaining a downwardly gravitating columnar mass of spent adsorbentcontinuously throughout a confined washing zone and a confined coolingzone thereabove, said cooling zone having greater lateral dimensionsthan said washing zone, introducing wash solvent into the lower sectionof said washing zone, passing said wash solvent a confined disengagingzone above said cooling zone and of lateral dimensions greater than thelateral dimensions of said cooling zone, passing solvent upwardlythrough the lower section of said disengaging zone as a column ofliquid, maintaining a gas space above said liquid column, passingaplurality of streams of spent adsorbent at a temperature above theboiling point of the solvent through a plurality of confined passagesterminating at a common level substantially below the upper surface ofsaid liquid column and substantially above the upper surface of saidcolumnar mass of adsorbent whereby the adsorbent will be cooled byindirect heat exchange with the upper portion of said liquod column to atemperature below the boiling range of said solvent and a portion of thesolvent in the liquid column will vaporize and pass into said gas space,discharging adsorbent from the lower ends of said passages and passingthe adsorbent downwardly onto the upper surface of said columnar mass,passing an inert gas into the disengaging zone with the plurality ofadsorbent streams at a pressure sufiicient to prevent liquid from saidcolumn from entering the lowor ends of said passages, withdrawing liquidsolvent from the upper section of said liquid column, withdrawingvaporized solvent from said gas space, withdrawing liquid solvent fromthe upper section of said cooling zone at a level adjacent to the uppersurface of said columnar mass, cooling the liquid solvent so withdrawn,introducing the cooled liquid solvent into said columnar mass at thelower end of said cooling zone, controlling the rate of solventwithdrawal from and introduction to said cooling zone and thetemperature of the intermediate cooling so that the upper section ofsaid columnar mass of adsorbent is reduced to a temperature below thetemperature at which more than fifty percent by weight of the colorbodies on the adsorbent would be removed by the wash solvent, andremoving washed adsorbent from the lower section of said columnar mass.

5. A continuous process for washing with a wash solvent a spentadsorbent of palpable particulate form bearing carbonaceouscontaminants, color bodies and mineral cycle oil and existing at atemperature above the boiling point of the solvent, which comprises:maintaining a downwardly gravitating columnar mass of spent adsorbentthroughout a confined washing zone, passing the wash solvent upwardlythrough said columnar mass to dissolve the cycle oil from the adsorbenttherein, discharging wash solvent with dissolved oil therein from theupper end of said columnar mass into the lower end of a confineddisengaging zone superimposed on said washing zone of greater lateraldimensions than said washing zone, passing liquid solvent upwardlythrough said disengaging zone as a liquid column, maintaining a gasspace in the upper section of the disengaging zone above the liquidcolumn, passing a plurality of streams of spent adsorbent at atemperature above the boiling point of the wash solvent into thedisengaging zone through a plurality of confined passages terminating ata level above the upper surface of the columnar mass and substantiallybelow the upper surface of the liquid column whereby the adsorbentstreams in the passages are cooled by indirect heat exchange with theliquid column to a temperature at least below the boiling range of saidsolvent and a portion of the solvent in the liquid column is vaporizedand passes into the gas space thereabove, maintaining the length of saidpassages such that substantially all of the solvent vaporization willoccur prior to adsorbent discharge from the passages, discharging cooledadsorbent from the lower ends of said passages onto the upper surface ofsaid columnar mass, withdrawing liquid solvent with dissolved oil fromthe upper section of said liquid column, withdrawing vaporized solventfrom said gas space, cooling the upper section of said columnar mass byindirect heat exchange with a cooling fluid to a temperature below thetemperature at which more than fifty percent by weight of the colorbodies on the adsorbent would be removed by the solvent and withdrawingwashed adsorbent from the lower section of said columnar mass.

6. In a continuous cyclic process for decoloring mineral oils wherein afresh oil feed is passed upwardly through a columnar mass of gravitatingadsorbent of palpable particulate form within a confined treating zoneat a rate and elevated temperature adjusted to efiect the desireddecolorization of the oil without substantial disruption of the columnarmass due to oil fiow therethrough and wherein spent adsorbent along withsome cycle oil and carbonaceous contaminants, including color bodies, issubjected to washing by a suitable wash solvent to remove the cycle oil,which wash solvent is also capable of removing excessive amounts of thecolor bodies from the spent adsorbent and wherein the washed adsorbentis regenerated by burning and recycled to the treating zone for re-use,the improved method of con ducting the washing of the adsorbent, whichcomprises: passing adsorbent downwardly through a confined washing zoneas a gravitating columnar mass; maintaining a body of liquid washsolvent within said washing zone above the upper surface of said mass;removing adsorbent from said treating zone and passing said adsorbentinto the washing zone as a plurality of confined streams at an elevatedtemperature, near the treating temperature, which is substantially abovethe boiling point of the wash solvent and above the temperature at whichexcessive amounts of color bodies are dissolved by the wash solvent fromthe adsorbent; passing said plurality of streams into indirect coolingheat exchange relationship with the liquid body within said washingzone; vaporizing a portion of the wash solvent in said liquid body bysaid heat exchange; removing the vaporized solvent from the washing zoneabove the liquid body and condensing said solvent and passing it as aliquid to an accumulation of wash solvent maintained exterior to saidwashing zone; maintaining said streams of adsorbent confined laterallyfrom a level above the surface of said liquid body to a level therebelowbut above the upper surface of said mass such that when said streamsbecome unconfined the adsorbent is at a temperature below that at whichsubstantial vaporization of solvent will occur and below the temperatureat which about fifty percent by weight of the color bodies on theadsorbent will be dissolved by the solvent; dropping the adsorbent fromsaid streams onto the upper surface of said columnar mass; passing washsolvent from said accumulation of wash solvent into the lower section ofsaid columnar mass and upwardly through said mass at a rate andtemperature suitable to dissolve cycle oil from the adsorbent and coolthe adsorbent mass to a suitable washing temperature; removing washsolvent with dissolved cycle oil from the upper section of said liquidbody and passing said solvent into a fractionation zone; separatingsolvent and cycle oil by fractionation within said fractionation zoneand condensing the solvent and returning it as a liquid to saidaccumulation of solvent; removing the cycle oil from said fractionationzone and passing said cycle oil into said treating zone.

7. A continuous process for removing mineral cycle oil, by means of awash solvent, from a spent adsorbent bearing carbonaceous contaminantsand color bodies and existing at a temperature above the initial boilingpoint of the solvent and above the temperature at which ex cessiveamounts of color bodies would re-dissolve in the wash solvent, whichprocess comprises: maintaining a column of said adsorbent in the lowersection of a confined washing zone; maintaining an accumulation of washsolvent exterior to said washing zone and passing wash solvent from saidaccumulation into the lower section of said column and passing thesolvent upwardly through said column to remove the cycle oil; passingthe liquid upwardly from the surface of said column and through a bodyof liquid maintained above said column and withdrawing the solvent andcycle oil from the upper section of said liquid body; withdrawing washedadsorbent substantially free of the cycle oil from the lower section ofsaid column so as to promote downward flow of the adsorbenttherethrough; passing spent adsorbent with cycle oil at said elevatedtemperature into the upper section of said washing zone and downwardlyonto the surface of said column as a plurality of confined streams inindirect heat exchange relationship with said liquid body to vaporize aportion of said solvent and cool said adsorbent to a temperature belowthe initial boiling point of said solvent and below the temperature atwhich fifty percent by weight of the color bodies on the adsorbent willdissolve in the solvent but above the desired average washingtemperature; withdrawing vaporized solvent from said washing zone;condensing said vaporized solvent and returning the condensed solvent tosaid accumulation of wash solvent; passing the solvent with dissolvedcycle oil after removal from said liquid body into a confinedfractionating zone and separating solvent and oil therein; condensingthe solvent so separated and returning condensed solvent to saidaccumulation of solvent; controlling the rate and temperature of thesolvent supplied to the lower section of said column to efiect a furthercooling of said adsorbent to the desired average washing temperature.

References Cited in the file of this patent UNITED STATES PATENTS2,482,137 Schutte Sept. 20, 1949 2,552,435 Knox et al. May 8, 19512,552,436 Bennett et al. May 8, 1951 2,571,380 Penick Oct. 16, 19512,602,044 Lupfer et al. July 1, 1952 2,631,727 Cichelli Mar. 17, 19532,696,305 Slover Dec. 7, 1954 2,696,462 Bodkin Dec. 7, 1954 2,701,786Evans et al. Feb. 8, 1955

1. A CONTINUOUS PROCESS FOR WASHING HOT, SPENT ADSORBENT OF PALPABLEPARTICULATE FORM HAVING BEEN USED FOR PURIFYING LIQUID X X HEARINGCARBONACEOUS CONTAMINANTS, COLOR BODIES AND CYCLE OIL, WHICH COMPRISES:MAINTAINING A DOWN WARDLY GRAVITATING COLUMNAR MASS OF ADSORBENT WITHINTHE LOWER SECTION OF A CONFINED WASHING ZONE, MAINTAINING A COLUMN OFLIQUID SOLVENT OF SUFFICIENT HEIGHT TO DISENGAGE ADSORBENT FROM THELIQUID SOLVENT ABOVE AND COLUMNAR MASS WITHIN THE UPPER SECTION OF THEWASHING ZONE, PASSING COOL WASHING SOLVENT UPWARDLY THROUGH SAIDCOLUMNAR MASS TO REMOVE CYCLE OIL FROM THE ADSORBENT THEREIN, PASSINGWASHING SOLVENT AFTER PASSAGE THROUGH THE COLUMNAR MASS UPWARDLY THROUGHSAID LIQUID COLUMN, INTRODUCING ADDITIONAL COOL WASHING SOLVENT AT ANINTERMEDIATE LEVEL IN SAID LIQUID COLUMN, PASSING A PLURALITY OF STREAMSOF HOT, SPENT ADSORBENT DOWNWARDLY THROUGH THE LIQUID COLUMN AND IN HEATEXCHANGE RELATIONSHIP THEREWITH TO EFFECT COOLING OF THE ADSORBENT ANDVAPORIZE A PORTION OF THE SOLVENT, DISCHARGING SAID STREAMS OF ADSORBENTONTO THE UPPER SURFACE OF SAID COLUMNAR MASS, REMOVING LIQUID SOLVENTFROM THE UPPER SECTION OF SAID COLUMN, MAINTAINING THE ADSORBENT STREAMSOUT OF LATERAL COMMUNICATION WITH THE PORTION OF THE LIQUID SOLVENTCOLUMN FROM WHICH LIQUID SOLVENT IS REMOVED DURING THAT PORTION OF THEHEAT EXCHANGE WHEREIN SOLVENT IS VAPORIZED, REMOVING VAPORIZED SOLVENTFROM THE UPPER SECTION OF SAID ZONE AT A LEVEL ABOVE THE UPPER SURFACEOF SAID COLUMN, AND REMOVING WASHED ADSORBENT FROM THE LOWER SECTION OFSAID COLUMNAR MASS.